Apparatus and method for transmitting harq ack/nack

ABSTRACT

Provided is a method and apparatus for transmitting an HARQ ACK/NACK. The method includes: in a TDD-FDD CA scheme; recognizing a 2-bit downlink (DL) downlink assignment index (DAI) field configured in a DL downlink control information (DCI) format, the DL DCI format indicating a Physical Downlink Shared Channel (PDSCH) transmission on the second serving cell, and the 2-bit DL DAI field indicating that ten downlink subframes for the second serving cell are associated with one uplink subframe; in response to received data, generating a Hybrid Automatic Repeat reQuest (HARQ) Acknowledgement/Negative Acknowledgement (ACK/NACK) signal, the HARQ ACK/NACK signal being indexed based on a value of the 2-bit DL DAI field; and transmitting the HARQ ACK/NACK signal through one uplink subframe of the first serving cell.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from and the benefit of Korean PatentApplication No. 10-2013-0144161, filed on Nov. 25, 2013, which is herebyincorporated by reference in its entirety.

BACKGROUND

1. Field

The present disclosure relates to wireless communication, and moreparticularly, to a method and apparatus for transmitting an HARQACK/NACK.

2. Discussion of the Background

Automatic repeat request (ARQ) is one of the schemes that enhancereliability of a wireless communication. The ARQ refers to a scheme inwhich a transmitter retransmits a data signal if a data signal receptionis failed at a receiver. Further, there is a scheme, hybrid automaticrepeat request (HARQ), which is a combination of Forward ErrorCorrection (FEC) and ARQ. A receiver that utilizes HARQ generallyattempts an error correction for a received data signal and determineswhether a retransmission needs to be performed by using an errordetection code. As the error detection code, Cyclic Redundancy Check(CRC) scheme may be used. If data signal error is not detected from thedetection process of CRC scheme, the receiver determines that a decodingprocess for the data signal is successful. In this case, the receivertransmits an Acknowledgement (ACK) signal to a transmitter. If datasignal error is detected from the detection process of CRC scheme, thereceiver determines that a decoding process for the data signal is notsuccessful. In this case, the receiver transmits a Not-Acknowledgement(NACK) signal to a transmitter. If the transmitter receives the NACKsignal, the transmitter may retransmit the data signal.

A wireless communication system may support Frequency Division Duplex(FDD) scheme and Time Division Duplex (TDD) scheme. In the FDD scheme,an uplink transmission and a downlink transmission may be simultaneouslyperformed in a cell because a carrier frequency for an uplink (UL)transmission is different from a carrier frequency for a downlink (DL)transmission exists. In the TDD scheme, with respect to one cell, anuplink transmission and a downlink transmission are distinguished fromeach other based on different time slots. In the TDD scheme, a basestation and a user equipment perform switching operations between atransmission mode and a reception mode because the same carrier is usedfor both an uplink transmission and a downlink transmission. In the TDDscheme, a Special Subframe may be added to provide a guard time forswitching between the transmission mode and the reception mode. TheSpecial Subframe may include Downlink Pilot Time Slot (DwPTS), GuardPeriod (GP), and Uplink Pilot Time Slot (UpPTS). According to the TDDscheme, resource amounts for the uplink transmission and resourceamounts for the downlink transmission may be asymmetrically assignedthrough various uplink (UL)-downlink (DL) configurations.

Currently, remaining frequency resources are scarce and varioustechnologies have been utilized in wide frequency bands because of thefrequency resource scarcity. For this reason, in order to provide awideband bandwidth for supporting higher data-rate requirements, each ofscattered bands has been configured to satisfy basic requirements tooperate an independent system and a carrier aggregation (CA) scheme,which aggregates various frequency bands into one system, has beenadopted. Here, each frequency band or carrier capable of an independentoperation may be defined as a component carrier (CC). According to theadoption of the carrier aggregation system, ACK/NACK signalscorresponding to a plurality of component carriers (CCs) need to betransmitted.

Recently, a Time Division Duplex (TDD)-Frequency Division Duplex (FDD)Carrier Aggregation (CA) that supports a CA and/or dual connectivity ofa FDD band (or carrier) and a TDD band (or carrier) has been considered.The TDD-FDD CA is referred to as a TDD-FDD joint operation. However,when it is assumed that a plurality of serving cells that are aggregatedby the CA exist, and a first serving cell is configured as TDD and asecond serving cell is configured as FDD, there may be difficulty intransmitting a HARQ ACK/NACK for downlink (DL) transmission on allsubframes of the second serving cell according to the TDD-FDD CA. Forexample, in a circumstance that allows only a control channel of thefirst serving cell (that is, a Physical Uplink Control Channel (PUCCH))for transmitting a HARQ ACK/NACK of the second serving cell, a largenumber of DL subframes of the second serving cell may exist inassociation with a single UL subframe of the first serving cell.Therefore, there is desire for a method of effectively transmitting aHARQ ACK/NACK, for the TDD-FDD CA.

SUMMARY

Exemplary embodiments of the present invention provide a method andapparatus for transmitting a HARQ ACK/NACK, and a method and apparatusfor receiving a HARQ ACK/NACK.

Exemplary embodiments of the present invention provide a method andapparatus for bundling a HARQ ACK/NACK associated with a new associatedsubframe with a HARQ ACK/NACK associated with a legacy associatedsubframe.

An exemplary embodiment of the present invention provides a method ofcommunicating control information between a base station and a userequipment (UE), the method including: establishing a Radio ResourceControl (RRC) connection with the base station through a first servingcell, the first serving cell supporting a Time Division Duplex (TDD)mode; receiving an RRC message from the base station through the firstserving cell, the RRC message including carrier aggregation (CA)configuration information, the CA configuration information includinginformation of a second serving cell supporting a Frequency DivisionDuplex (FDD) mode, and the first serving cell and the second servingcell being aggregated by a TDD-FDD CA scheme; recognizing a 2-bitdownlink (DL) downlink assignment index (DAI) field configured in a DLdownlink control information (DCI) format, the DL DCI format indicatinga Physical Downlink Shared Channel (PDSCH) transmission on the secondserving cell, and the 2-bit DL DAI field indicating that ten downlinksubframes for the second serving cell are associated with one uplinksubframe; receiving, at the UE, at least one of a Physical DownlinkControl Channel (PDCCH) and an Enhanced PDCCH (EPDCCH), the at least oneof the PDCCH and the EPDCCH including the DL DCI format; receiving, atthe UE, data through the first serving cell and the second serving cell;in response to the received data, generating a Hybrid Automatic RepeatreQuest (HARQ) Acknowledgement/Negative Acknowledgement (ACK/NACK)signal, the HARQ ACK/NACK signal being indexed based on a value of the2-bit DL DAI field; and transmitting the HARQ ACK/NACK signal throughone uplink subframe of the first serving cell.

An exemplary embodiment of the present invention provides a method ofcommunicating control information between a base station and a userequipment (UE), the method including: establishing a Radio ResourceControl (RRC) connection with the UE through a first serving cell, thefirst serving cell supporting a Time Division Duplex (TDD) mode;transmitting an RRC message to the UE through the first serving cell,the RRC message including carrier aggregation (CA) configurationinformation, the CA configuration information including information of asecond serving cell supporting a Frequency Division Duplex (FDD) mode,and the first serving cell and the second serving cell being aggregatedby a TDD-FDD CA scheme; configuring a 2-bit downlink (DL) downlinkassignment index (DAI) field in a DL downlink control information (DCI)format, the DL DCI format indicating a Physical Downlink Shared Channel(PDSCH) transmission on the second serving cell, and the 2-bit DL DAIfield indicating that ten downlink subframes for the second serving cellare associated with one uplink subframe; transmitting, to the UE, atleast one of a Physical Downlink Control Channel (PDCCH) and an EnhancedPDCCH (EPDCCH), the at least one of the PDCCH and the EPDCCH includingthe DL DCI format; transmitting, to the UE, data through the firstserving cell and the second serving cell; and in response to thetransmitted data, receiving a Hybrid Automatic Repeat reQuest (HARQ)Acknowledgement/Negative Acknowledgement (ACK/NACK) signal, the HARQACK/NACK signal being indexed based on a value of the 2-bit DL DAIfield. The HARQ ACK/NACK signal is received through one uplink subframeof the first serving cell.

Under a circumstance of CA of a TDD-based cell (or carrier) and anFDD-based cell (or carrier), a base station and a terminal may implementan effective HARQ ACK/NACK transmitting method.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 illustrates a wireless communication system according to anexemplary embodiment of the present invention.

FIG. 2 illustrates an example of a protocol structure for supporting amulti-carrier system according to an exemplary embodiment of the presentinvention.

FIG. 3 illustrates an example of a radio frame structure according to anexemplary embodiment of the present invention.

FIG. 4 illustrates a case of an inter-band CA of serving cells havingdifferent TDD UL-DL configurations.

FIG. 5 illustrates an example of a deployment scenario according to anexemplary embodiment of the present invention.

FIG. 6 illustrates an example of an FDD-TDD CA scheme according to anexemplary embodiment of the present invention.

FIG. 7 illustrates examples of capabilities of a terminal for a TDD-FDDCA according to an exemplary embodiment of the present invention.

FIG. 8 illustrates an example of a DL HARQ timing when a terminal forwhich a TDD-FDD CA is configured operates based on self-scheduling.

FIG. 9 illustrates an example of a DL HARQ timing when a terminal forwhich a TDD-FDD CA is configured operates based on cross-carrierscheduling.

FIGS. 10 and 11 are diagrams illustrating a new DL HARQ timing accordingto an exemplary embodiment of the present invention.

FIG. 12 is a diagram illustrating a legacy HARQ ACK/NACK that is bundledwith a new HARQ ACK/NACK according to an exemplary embodiment of thepresent invention.

FIG. 13 is a diagram illustrating a method of bundling HARQ ACK/NACKsbased on a Downlink Assignment Index (DAI) according to an exemplaryembodiment of the present invention.

FIG. 14 is a diagram illustrating HARQ ACK/NACK bundling according to anexemplary embodiment of the present invention.

FIG. 15 is a diagram illustrating HARQ ACK/NACK bundling according toanother exemplary embodiment of the present invention.

FIG. 16 is a diagram illustrating HARQ ACK/NACK bundling according toanother exemplary embodiment of the present invention.

FIG. 17 is a diagram illustrating a case in which an identical DAI valueis applied to subframes that are bundled according to an exemplaryembodiment of the present invention.

FIG. 18 is a flowchart illustrating a HARQ ACK/NACK transmission methodaccording to an exemplary embodiment of the present invention.

FIG. 19 illustrates an example of mapping a PUCCH to physical RBs.

FIG. 20 is a block diagram illustrating a terminal and a base stationaccording to an exemplary embodiment of the present invention.

DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENTS

Exemplary embodiments of the present invention will be described morefully hereinafter with reference to the accompanying drawings, in whichexemplary embodiments of the invention are shown. Throughout thedrawings and the detailed description, unless otherwise described, thesame drawing reference numerals are understood to refer to the sameelements, features, and structures. In describing the exemplaryembodiments, detailed description on known configurations or functionsmay be omitted for clarity and conciseness.

Further, the terms, such as first, second, A, B, (a), (b), and the likemay be used herein to describe elements in the description herein. Theterms are used to distinguish one element from another element. Thus,the terms do not limit the element, an arrangement order, a sequence orthe like. It will be understood that when an element is referred to asbeing “on”, “connected to” or “coupled to” another element, it can bedirectly on, connected or coupled to the other element or interveningelements may be present.

Further, the description herein is related to a wireless communicationnetwork, and an operation performed in a wireless communication networkmay be performed in a process of controlling a network and transmittingdata by a system that controls a wireless network (e.g., a base station)or may be performed in a user equipment connected to the wirelesscommunication network.

FIG. 1 is a diagram illustrating a wireless communication systemaccording to an exemplary embodiment of the present invention.

According to FIG. 1, a wireless communication system 10 is widelydeployed in order to provide diverse telecommunication services, such asvoice and packet data. A wireless communication system includes at leastone base station 11 (BS). Each BS 11 provides telecommunication serviceto certain cells 15 a, 15 b, and 15 c. A cell may again be divided intomultiple sectors.

User equipment 12 (mobile station, MS) may be located at a certainlocation or mobile, and may also be referred to as different terms,including UE (user equipment), MT (mobile terminal), UT (user terminal),SS (subscriber station), wireless device, PDA (personal digitalassistant), wireless modem, and handheld device. A base station 11 mayalso be referred to as eNB (evolved-NodeB), BTS (Base TransceiverSystem), Access Point, femto base station, Home nodeB, and relay. A cellinclusively refers to various coverage areas, such as mega cell, macrocell, micro cell, pico cell, and femto cell.

Hereinafter, the term downlink refers to communication from a basestation 11 to a UE 12, and the term uplink refers to communication froma UE 12 to a base station 11. For downlink, a transmitter may be part ofa base station 11, and a receiver may be part of a UE 12. For uplink, atransmitter may be part of a UE 12 and a receiver may be part of a basestation 11. There is no limitation in the multiple access method appliedto a wireless communication system. Diverse methods can be used,including CDMA (Code Division Multiple Access), TDMA (Time DivisionMultiple Access), FDMA (Frequency Division Multiple Access), OFDMA(Orthogonal Frequency Division Multiple Access), SC-FDMA (SingleCarrier-FDMA), OFDM-FDMA, OFDM-TDMA, OFDM-CDMA. Uplink transmission anddownlink transmission can use either TDD (Time Division Duplex), whichuses different time locations for transmissions, or FDD (FrequencyDivision Duplex), which uses different frequencies for transmissions.

Carrier Aggregation (CA), which is also referred to as spectrumaggregation or bandwidth aggregation, supports multiple carriers. Eachindividual unit carrier, which is aggregated by carrier aggregation, isreferred to as Component Carrier (CC). Each component carrier is definedby bandwidth and center frequency. CA is introduced to supportincreasing throughput, to prevent cost increase due to the introductionof the wideband radio frequency and to ensure the compatibility with theexisting system. For example, if five component carriers are allocatedas granularity that has a carrier unit with 20 MHz bandwidth, it cansupport 100 MHz bandwidth at maximum.

CA may be divided as contiguous carrier aggregation, which is made amongcontinuous CCs, and non-contiguous carrier aggregation, which is madeamong non-continuous CCs. The number of carriers aggregated betweenuplink and downlink may be configured differently. It is referred to assymmetric aggregation when there are equal number of downlink CCs anduplink CCs, and it is referred to as asymmetric aggregation when thenumber of downlink CCs and the number of uplink CCs are not equal.

The size of component carriers (in other words, bandwidth) may bedifferent. For example, if five component carriers are used to form 70MHz band, 5 MHz component carrier (carrier #0)+20 MHz component carrier(carrier #1)+20 MHz component carrier (carrier #2)+20 MHz componentcarrier (carrier #3)+5 MHz component carrier (carrier #4) may beaggregated together.

Hereinafter, a multiple carrier system includes the system that supportscarrier aggregation. Contiguous CA and/or non-contiguous CA may be usedin the multiple carrier system; in addition, both symmetric aggregationand asymmetric aggregation may be used in the multiple carrier system aswell. A serving cell may be defined as a component frequency band basedon multiple CC system which may be aggregated by CA. A serving cell mayinclude a primary serving cell (PCell) and a secondary serving cell(SCell). A PCell means a serving cell which provides security input andNon-Access Stratum (NAS) mobility information on Radio Resource Control(RRC) establishment or re-establishment state. Depends on the capabilityof a user equipment, at least one cell may be used together with a PCellto form an aggregation of serving cells, the cell used with a PCell isreferred to as an SCell. An aggregation of serving cells whichconfigured for a user equipment may include one PCell, or one PCelltogether with at least one SCell.

Downlink component carrier corresponding to a PCell refers to Downlink(DL) Primary Component Carrier (PCC), and uplink component carriercorresponding to a PCell refers to Uplink (UL) PCC. In addition,downlink component carrier corresponding to an SCell refers to a DLSecondary Component Carrier (SCC), and an uplink component carriercorresponding to an SCell refers to a UL SCC. Only DL CC or UL CC maycorrespond to a serving cell, or a DL CC and an UL CC together maycorrespond to a serving cell.

FIG. 2 is a diagram illustrating an example of a protocol structure forsupporting a multi-carrier system according to an exemplary embodimentof the present invention.

Referring to FIG. 2, common Medium Access Control (MAC) entity 210manages physical layer 220 which uses a plurality of carriers. The MACmanagement message, transmitting through a certain carrier, may beapplied to other carriers. That is, the MAC management message is amessage which controls other carriers including the certain carriermentioned above. A physical layer 220 may be operated by the TimeDivision Duplex (TDD) and/or the Frequency Division Duplex (FDD).

There are some physical control channels used in physical layer 220. Asa DL physical channel, a Physical Downlink Control Channel (PDCCH)informs to a UE with regard to resource allocation of a Paging Channel(PCH) and a Downlink Shared Channel (DL-SCH), and a Hybrid AutomaticRepeat Request (HARQ) information related to a DL-SCH. The PDCCH maycarry uplink grant which informs a resource allocation of uplinktransmission to a UE. The DL-SCHO is mapping to a Physical DownlinkShared Channel (PDSCH). A Physical Control Format Indicator Channel(PCFICH), which transmits every sub-frame, informs the number of OFDMsymbols used on the PDCCHs to a user equipment. A Physical Hybrid ARQIndicator Cannel (PHICH), as a DL channel, carries the HARQ ACK/NACKsignals as a response to uplink transmission. As a UL physical channel,Physical Uplink Control Channel (PUCCH) may carry UL controllinginformation such as ACK (Acknowledgement)/NACK (Non-acknowledgement) orChannel Status Information (CSI) which includes Channel QualityIndicator (CQI), Precoding Matrix Index (PMI), Precoding Type Indicator(PTI) or Rank Indication (RI). The Physical Uplink Shared Channel(PUSCH) carries the Uplink Shared Channel (UL-SCH). The Physical RandomAccess Channel (PRACH) carries random access preamble.

A plurality of the PDCCH may be transmitted in the controlled region,and a user equipment can monitor a plurality of the PDCCH. The PDCCH istransmitted on either one Control Channel Element (CCE) or anaggregation of several consecutive CCEs. The CCE is a logical allocationunit used to provide PDCCH with a code rate based on the state of radiochannel. The CCE corresponds to a plurality of Resource Element Groups.The format of the PDCCH and the number of available bits for the PDCCHare determined according to the relationship between the number of CCEsand a code rate provided by the CCEs.

Control information carried on the PDCCH is referred to as DownlinkControl Information (DCI). The following table 1 shows DCI pursuant toseveral formats.

TABLE 1 DCI Format Description 0 Used for PUSCH scheduling in uplinkcell 1 Used for one PDSCH codeword scheduling in one cell 1A Used forbrief scheduling of one PDSCH codeword in one cell or random accessprocess initialized by the PDCCH command 1B Used for a brief schedulingof one PDSCH codeword with precoding information in one cell 1C Used forone PDSCH codeword brief scheduling in one cell or the notification ofMCCH change 1D Used for a brief scheduling of one PDSCH codeword in onecell including precoding or power offset information 2 Used for thePDSCH scheduling of the user equipment configured of spartialmultiplexing mode. 2A Used for the PDSCH scheduling of the userequipment configured of large delay CDD mode 2B Used in the transmissionmode 8 (a double layer transmission, etc) 2C Used in the transmissionmode 9 (a multi layer transmission) 2D Used in the transmission mode 10(CoMP) 3 Used for the tramission of TPC commands for PUCCH and PUSCHincluding 2-bit power adjustment 3A Used for the tramission of TPCcommands for PUCCH and PUSCH including single-bit power adjustment 4Used for the PUSCH scheduling in the uplink multi-antenna porttransmission cell

Referring to Table 1, There are DCI formats such as format 0 used forthe PUSCH scheduling in uplink cell, format 1 used for one PDSCHcodeword scheduling in one cell, format 1A used for compact schedulingof one PDSCH codeword, format 2 used for the PDSCH scheduling inclosed-loop spartial multiplexing mode, format 2B used for the PDSCHscheduling in open-loop spartial multiplexing mode, format 2B used inthe transmission mode 8, format 2C used in the transmission mode 9,format 2D used in the transmission mode 10, format 3 and 3A used for theuplink transmission of TPC commands for the PUCCH and the PUSCH, andformat 4 used for the PUSCH scheduling in the uplink multi-antenna porttransmission cell.

Each field of DCI is sequentially mapped to n number of information bitsa₀ or a_(n-1). For example, the DCI is mapped to a total length of 44bits of information bits, each field of DCI is mapped sequentially to a₀or a₄₃. DCI formats 0, 1A, 3, 3A may have the same payload size. DCIformat 0, 4 may be referred to as the Uplink grant (UL grant).

Cross-carrier scheduling is a scheduling method capable of performingresource allocation of a PDSCH transmitted by using a different carrierthrough a PDCCH transmitted through a specific CC and/or resourceallocation of a PUSCH transmitted by using another CC other than a CCbasically linked to the specific CC. That is, the PDCCH and the PDSCHmay be transmitted through different DL CCs, and the PUSCH may betransmitted through a UL CC other than a UL CC linked to a DL CC onwhich a PDCCH including a UL grant is transmitted.

During cross-carrier scheduling, a user equipment only receivesscheduling information (such as UL grant) through a serving cell (orCC). Hereinafter, a serving cell (or CC) performing cross-carrierscheduling may refer to scheduling cell (or CC), and a serving cellbeing scheduled by scheduling cell may refer to scheduled cell (or CC).Scheduling cell may refer to ordering cell, and scheduled cell may referto following serving cell. For example, a scheduled cell may bescheduled by a scheduling cell. Scheduling information for the scheduledcell may be received through the scheduling cell.

As such, in a system supporting the cross-carrier scheduling, a carrierindicator is necessary to report which DL CC/UL CC was used to transmitthe PDCCH/EPDCCH which indicates the PDSCH/PUSCH transmission. A fieldincluding the carrier indicator is hereinafter called a carrierindication field (CIF). Hereinafter, configuration of CIF may mean thatconfiguration of cross-carrier scheduling.

The aforementioned cross-carrier scheduling may be classified into theDL cross-carrier scheduling and UL cross-carrier scheduling. The DLcross-carrier scheduling implies a case where the CC for transmittingthe PDCCH/EPDCCH including resource allocation information for the PDSCHtransmission and other information is different from a CC fortransmitting the PDSCH. The UL cross-carrier scheduling implies a casewhere a CC for transmitting the PDCCH/EPDCCH including a UL grant forthe PUSCH transmission is different from the DL CC linked to the UL CCfor transmitting the PUSCH.

FIG. 3 is a diagram illustrating an example of a radio frame structureaccording to an exemplary embodiment of the present invention. Thediagram illustrates a FDD radio frame structure and a TDD radio framestructure.

Referring to FIG. 3, one radio frame includes 10 subframes, and onesubframe includes 2 consecutive slots.

In the FDD, both carrier used for UL transmission and carrier used forDL transmission exist, and UL transmission and DL transmission may beperformed simultaneously in one cell.

In the TDD, on one cell basis, UL transmission and DL transmission canalways distinguished in time. Because a same carrier is used for both ULtransmission and DL transmission, a base station and user equipmentrepeatedly switches between the transmission mode and the receptionmode. In the TDD, special subframe may be placed to provide a guard timewhich is for switching mode between the transmission and the reception.Special subframe, as shown, includes a downlink pilot time slot (DwPTS),a guard period (GP), and an uplink pilot time slot (UpPTS). The DwPTS isused in the UE for initial cell search, synchronization, or channelestimation. The UpPTS is used in the BS for channel estimation anduplink transmission synchronization of the UE. The GP is needed to avoidinterference between an uplink and a downlink, and during the GP, no ULtransmission and DL transmission occurs.

Table 2 shows an example of UL/DL configuration of radio frame. UL/DLconfiguration defines reserved subframe for UL transmission or reservedsubframe for DL transmission. That is, UL/DL configuration informs therules how the uplink and the downlink are allocated (or reserved) inevery subframe of one radio frame.

TABLE 2 Uplink- Switch- downlink point Subframe number configurationperiodicity 0 1 2 3 4 5 6 7 8 9 0 5 ms D S U U U D S U U U 1 5 ms D S UU D D S U U D 2 5 ms D S U D D D S U D D 3 10 ms  D S U U U D D D D D 410 ms  D S U U D D D D D D 5 10 ms  D S U D D D D D D D 6 5 ms D S U U UD S U U D

In Table 2, ‘D’ denotes a DL subframe, ‘U’ denotes a UL subframe, and‘U’ denotes a special subframe. As shown to Table 2, subframe 0 and 5are always allocated to DL transmission, and subframe 2 is alwaysallocated to UL-transmission. As shown to Table 2, each UL-DLconfiguration has a different number and position of DL subframe and ULsubframe in one radio frame. Through diverse UL-DL configuration, theamount of resource allocated to UL/DL transmission may be givenasymmetrically. To avoid severe interference between UL and DL amongcells, neighboring cells generally have same UL-DL configuration.

The point changing from DL to UL or the point changing from UL to DL isreferred to as the switching point. The switch-point periodicity, whichis either 5 ms or 10 ms, means a repeating period of the same changingaspect between the UL subframe and DL subframe. For example, referringto the UL/DL configuration 0, subframe from 0 to 4 changesD->S->U->U->U, subframe from 5 to 9 changes, as same as before,D->S->U->U->U. Since one subframe is 1 ms, the switch-point periodicityis 5 ms. That is, the switch-point periodicity is shorter than thelength of one radio frame (10 ms), the changing aspect in the radioframe is repeated for one time.

The UL-DL configuration in above Table 2 may be transmitted from a basestation to a user equipment through system information. The base stationmay inform a UL/DL allocation status change in a radio frame to a UE bytransmitting the index of the UL/DL configuration whenever the UL/DLconfiguration changes. Or the UL/DL configuration may be controlinformation which is transmitted to every UE in the cell throughbroadcast channel.

Hereinafter, HARQ will be described. A base station transmits a DLgrant, which is PDSCH scheduling information, to a terminal through aPDCCH or an EPDCCH, and transmits a PDSCH. Then, the terminal transmitsa HARQ Acknowledgement/Non-acknowledgement (ACK/NACK) with respect to aDL-SCH Transport Block (TB) received through the PDSCH, trough a PUCCHat a predetermined timing. The base station repeats the process during apredetermined period of time until receiving a HARQ ACK signal from theterminal, which is referred to as HARQ. In other words, from theperspective of the base station, HARQ refers to an operation thatreceives a HARQ ACK/NACK with respect to a DL transmission from theterminal, and executes a DL retransmission or a new transmission. Fromthe perspective of the terminal, HARQ refers to an operation thattransmits a HARQ ACK/NACK with respect to a DL transmission to the basestation, and receives a DL retransmission or a new transmission.

For the FDD, when a terminal detects a PDSCH transmission for thecorresponding terminal from a subframe n−4, the terminal transmits aHARQ response in a subframe n.

For TDD, when PDSCH transmission indicated by detection of acorresponding PDCCH/EPDCCH exists in a subframe n−k, or when aPDCCH/EPDCCH indicating Semi-Persistent Scheduling (SPS) release exists,the terminal transmits a HARQ response in a subframe n. In thisinstance, DL HARQ ACK/NACK timings may be listed as shown in Table 3.

TABLE 3 UL/DL subframe n configuration 0 1 2 3 4 5 6 7 8 9 0 — — 6 — 4 —— 6 — 4 1 — — 7, 6 4 — — — 7, 6 4 — 2 — — 8, 7, 4, 6 — — — — 8, 7, 4, 6— — 3 — — 7, 6, 11 6, 5 5, 4 — — — — — 4 — — 12, 8, 7, 11 6, 5, 4, 7 — —— — — — 5 — — 13, 12, 9, 8, 7, 5, 4, 11, 6 — — — — — — — 6 — — 7 7 5 — —7 7 —

In Table 3, n denotes a subframe number, and a “DL subframe set”associated with a subframe of the corresponding number is determined byK={k₀, k₁, . . . , K_(M-1)}. n−k denotes an index of a subframe that isk subframes before from an n^(th) subframe, and indicates a DL subframe(that is, a DL HARQ timing) associated with a current subframe. Theassociated DL subframe indicates a subframe that delivers a PDSCH whichis the basis of the determination on a HARQ ACK/NACK signal. M denotesthe number of elements of a set K defined in table 3, and indicates thenumber of DL subframes associated with the n^(th) subframe, or abundling window size.

For example, when UL-DL configuration 1 is applied to a serving cell, Mof a DL subframe set K associated with a subframe 2 is 2 (M=2), k₀=7,and k₁=6. Therefore, DL subframes (or DL HARQ timings) associated withthe subframe 2 of the corresponding serving cell are a subframe 5 (2-k₀)and a subframe 6 (2-k₁) of a previous radio frame.

FIG. 4 illustrates a case of an inter-band CA of serving cells havingdifferent TDD UL-DL configurations.

Referring to FIG. 4, component carriers that configure a CA with aterminal are CC1 and CC2, the CC1 may be configured as UL-DLconfiguration #1 and CC2 may be configured as UL-DL configuration #2,for the purpose of traffic adaption (semi-static) and avoidance ofinterference between heterogeneous networks. For example, to avoid aninterference issue with other TDD systems (for example, TDS-CDMA, WiMAX,and the like) that co-exist in an identical band, different UL-DLconfigurations may be required in an inter-band CA. In addition, when aUL-DL configuration including a large number of UL subframes is appliedto a low frequency band, and a UL-DL configuration including a smallnumber of UL subframes is applied to a high frequency band, it may behelpful for the coverage enhancement.

For the TDD, when a terminal is configured with one or more servingcells, at least two serving cells have different UL-DL configurations,and one of the serving cells is a PCell, a UL-DL configuration of thePCell is a DL reference UL-DL configuration. Here, the DL referenceUL-DL configuration indicates a UL-DL configuration used as a referencefor a DL HARQ timing of a serving cell.

Meanwhile, for the TDD, when a terminal is configured with two or moreserving cells, at least two serving cells have different UL-DLconfigurations, and one of the serving cells is an SCell, a DL referenceUL-DL configuration for the SCell is as shown in the following Table 4.

TABLE 4 (Primary cell UL/DL configuration, Secondary DL-reference UL/DLSet # cell UL/DL configuration) configuration Set 1 (0, 0) 0 (1, 0), (1,1), (1, 6) 1 (2, 0), (2, 2), (2, 1), (2, 6) 2 (3, 0), (3, 3), (3, 6) 3(4, 0), (4, 1), (4, 3), (4, 4), (4, 6) 4 (5, 0), (5, 1), (5, 2), (5, 3),(5, 4), (5, 5), (5, 6) 5 (6, 0), (6, 6) 6 Set 2 (0, 1), (6, 1) 1 (0, 2),(1, 2), (6, 2) 2 (0, 3), (6, 3) 3 (0, 4), (1, 4), (3, 4), (6, 4) 4 (0,5), (1, 5), (2, 5), (3, 5), (4, 5), (6, 5) 5 (0, 6) 6 Set 3 (3, 1), (1,3) 4 (3, 2), (4, 2), (2, 3), (2, 4) 5 Set 4 (0, 1), (0, 2), (0, 3), (0,4), (0, 5), (0, 6) 0 (1, 2), (1, 4), (1, 5) 1 (2, 5) 2 (3, 4), (3, 5) 3(4, 5) 4 (6, 1), (6, 2), (6, 3), (6, 4), (6, 5) 6 Set 5 (1, 3) 1 (2, 3),(2, 4) 2 (3, 1), (3, 2) 3 (4, 2) 4

In Table 4, based on a pair of a PCell UL-DL configuration and an SCellUL-DL configuration, the DL reference UL-DL configuration for the SCellmay be indicated.

For example, when the pair of the PCell UL-DL configuration and theSCell UL-DL configuration of Table 4 belongs to Set 1, the DL referenceUL-DL configuration for the SCell applies a DL HARQ timing based on theDL reference UL-DL configuration for Set 1. In this instance, it isirrespective of a scheduling method.

Alternatively, in a case in which self-scheduling is set for a terminal,when the pair of the PCell UL-DL configuration and the SCell UL-DLconfiguration belongs to Set 2 or Set 3, a DL reference UL-DLconfiguration of Set 2 or Set 3 is used. Here, when self-scheduling isset for the terminal, it indicates that the terminal is not set tomonitor a PDCCH/EPDCCH of another serving cell for scheduling of acorresponding serving cell.

Alternatively, in a case in which cross-carrier scheduling is set for aterminal, when the pair of the PCell UL-DL configuration and the SCellUL-DL configuration belongs to Set 4 or Set 5, a DL reference UL-DLconfiguration of Set 4 or Set 5 is used. Here, when cross-carrierscheduling is set for the terminal, it indicates that the terminal isset to monitor a PDCCH/EPDCCH of another serving cell for scheduling ofa corresponding serving cell.

That is, the DL reference UL-DL configuration of Set 1 is applied when acorresponding pair is satisfied, irrespective of whether a CarrierIndicator Field (CIF) indicating a carrier associated with scheduling isconfigured. Conversely, Set 2 and Set 3 are applied to only a terminalfor which a CIF is not configured, and Set 4 and Set 5 are applied toonly a terminal for which a CIF is configured.

An ACK/NACK signal with respect to a PDCCH/EPDCCH that indicates a PDSCHor SPS release corresponding to each of a plurality of serving cells ofa CA may be transmitted at the above described HARQ timing.

FIG. 5 illustrates an example of a deployment scenario according to anembodiment of the present invention.

Referring to FIG. 5, a plurality of macro cells and a plurality of smallcells (for example, picocells or femtocells) may be disposed, having anidentical frequency or adjacent frequencies. (a) A deployment scenarioin which a plurality of outdoor small cells use a frequency bandidentical to a frequency band of macro cells (b) A deployment scenarioin which a plurality of small cells use an identical frequency band,macro cells use a frequency band adjacent to the frequency band of thesmall cells, all of the macro cells have an identical UL-DLconfiguration, and the small cells may adjust a UL-DL configuration

FIG. 6 is a diagram illustrating an example of an FDD-TDD CA methodapplication according to an exemplary embodiment of the presentinvention.

Referring FIG. 6, in case of the TDD legacy UE 620, wirelesscommunication service can only be received through the TDD band, and incase of the legacy FDD UE 640, wireless communication service can onlybe received through the FDD band. On other hands, in case of the FDD-TDDCA capable UE 600, wireless communication service may be receivedthrough the FDD and the TDD bands, and also the CA based wirelesscommunication service is provided through the TDD band carrier and theFDD band carrier.

For those aforementioned TDD-FDD CA, for example, the followingdeployments may be considered.

As an example, the FDD base station and the TDD base station isco-located (for example, CA scenarios 1 through 3), or the FDD basestation and the TDD based station is not co-located, but connectedthrough the ideal backhaul (for example, CA scenario 4).

As another example, the FDD base station and the TDD base station is notco-located, and connected through non-ideal backhaul (for example, smallcell scenario 2a, 2b, and macro-macro scenario).

However, for the TDD-FDD CA, it is desirable that the TDD base stationand the FDD base station is connected through the ideal backhaul and theTDD cell and the FDD cell is operated as synchrozied.

In addition, for the TDD-FDD CA, following prerequisite may beconsidered.

First, a UE supporting the FDD-TDD CA may access to the legacy FDDsingle mode carrier and the legacy TDD single mode carrier.

Second, the legacy FDD UEs and the UEs supporting the TDD-FDD CA maycamp on and be connected to the FDD carrier which is the part of theaforementioned FDD/TDD network.

Third, the legacy TDD UEs and the UEs supporting the TDD-FDD CA may campon and be connected to the TDD carrier which is the part of theaforementioned FDD/TDD joint operation network.

Fourth, a network architecture enhancement in order to facilitate theFDD-TDD CA, for example, with regard to the non-ideal backhaul, may beconsidered. However, keeping the minimal network architecture changesshould be considered since it is still essential in operator'sperspective.

In addition, as a UE to support the TDD-FDD CA, following UE abilitiesmay be considered.

FIG. 7 is examples of UE capabilities for the TDD-FDD CA according to anexemplary embodiment of the present invention.

Referring to FIG. 7, (a) indicates that a UE is supporting the CAbetween the TDD carrier and the FDD carrier; (b) indicates that a UE issupporting the CA between the TDD carrier and the FDD DL carrier; and(c) indicates that a UE is supporting the CA between the TDD carrierwith a DL subframe and the FDD carrier.

As mentioned above, a UE may support different types of the TDD-FDD CA,and further, it may perform simultaneous reception (that is, DLaggregation) from the FDD and TDD carriers. Secondly, a UE may performsimultaneous transmission (that is, UL aggregation) from the FDD and TDDcarriers, and thirdly, a UE may perform simultaneous transmission andreception (that is, full duplex) from the FDD and TDD carriers.

In the above described TDD-FDD CA, a maximum number of aggregatedComponent Carriers (CCs) may be, for example, 5. In addition, anaggregation of different UL-DL configurations for TDD carriers ofdifferent bands may be supported.

In this instance, the FDD-TDD CA-capable terminal may support theTDD-FDD DL CA and may not support the TDD-FDD UL CA. The FDD-TDDCA-capable terminal may support at least the TDD-FDD DL CA, but may ormay not support the TDD-FDD UL CA.

Meanwhile, a UE may configure a dual connectivity through two or morebase stations among base stations that may include at least one servingcell. A dual connectivity is an operation that the UE utilizes wirelessresources provided by at least two different network points (forexample, a macro base station or a small base station) in RRC CONNECTEDmode. In this case, those abovementioned two different network pointsmay be connected by a non-ideal backhaul. Here, one of thoseabovementioned two different network points may refer to a macro basestation (or a master base station or an anchor base station), remainingnetwork points may refer to small base stations (or secondary basestations or assisting base stations, or slave base stations).

A UE, as mentioned above, may support a TDD-FDD joint operation when theCA and/or dual connectivity is configured to the UE. Hereinafter,aspects of the present invention will be explained based on a case wherea UE configured to the CA, but aspects of the present invention may beapplied to a case of a UE configured to the dual connectivity.

The TDD-FDD CA may include an environment in which a PCell operates asTDD and an SCell operates as FDD. The environment is irrespective of ascheduling scheme, but has a high probability of being provided whenself-scheduling is used. Hereinafter, a DL HARQ timing to be applied toan SCell based on a relationship with a PCell which is a PUCCHtransmission serving cell, will be described.

FIG. 8 illustrates an example of a DL HARQ timing when a terminal forwhich a TDD-FDD CA is configured operates based on self-scheduling. FIG.8 corresponds to a case in which a PCell is configured as TDD UL-DLconfiguration 1, and an SCell is configured as FDD.

When the terminal operates based on self-scheduling as shown in FIG. 8,an existing FDD DL HARQ timing may be applied to an SCell. However, inthis instance, the PCell which is a PUCCH transmission serving cell isconfigured as TDD and thus, this may result in failure of transmissionof a PDSCH in many DL subframes by taking into account of a location ofa UL subframe of the PCell. This may deteriorate a peak data rate that asingle terminal may support.

FIG. 9 illustrates an example of a DL HARQ timing when a terminal forwhich a TDD-FDD CA is configured operates based on cross-carrierscheduling. FIG. 9 corresponds to a case in which a PCell is configuredas TDD UL-DL configuration 1, and an SCell is configured as FDD.

When a cross-carrier scheduling is configured for the terminal and anexisting FDD DL HARQ timing is applied to the SCell, as shown in FIG. 9,the PCell which is a PUCCH transmission serving cell is configured asTDD and thus, this may result in failure of transmission of a PDSCH inmany DL subframes due to a lack of a DL scheduling indicating method inaddition to the drawback of the PCell for the PUCCH transmission. Forexample, in a case of self-scheduling, a terminal may receive a PDSCHand a PDCCH/EPDCCH that indicates the PDSCH on a subframe 3 of theSCell, and may transmit a HARQ ACK/NACK with respect to the reception toa base station on a subframe 7 of the PCell. However, in a case ofcross-carrier scheduling, a subframe 3 of the PCell having TDD UL-DLconfiguration 1 is a DL subframe and thus, a PDCCH/EPDCCH indicating thePDSCH is not transmitted and thus, the terminal may not transmit a HARQACK/NACK on the subframe 7 of the PCell.

As illustrated in FIGS. 8 and 9, a drawback of a DL HARQ timing for aPDSCH transmitted on an SCell (FDD) exists in all scheduling schemes inthe TDD-FDD CA environment. To overcome the drawback, a new DL HARQtiming for an SCell needs to be designed. Designing a new DL HARQ timingincludes adding a new DL HARQ timing for the TDD or employing a new DLHARQ timing for the TDD-FDD CA.

By taking into consideration the designed new HARQ timing, there is adesire for a method and apparatus for transmitting a HARQ ACK/NACK withrespect to a PDSCH of all of the DL subframes on a serving cell thatoperates based on FDD. Therefore, the present invention provides animproved method and apparatus for transmitting a HARQ ACK/NACK, whichmay be applicable to the TDD-FDD CA. In addition, the present inventionprovides an improved method and apparatus for receiving a HARQ ACK/NACK,which may be applicable to the TDD-FDD CA.

At least one of the following conditions may be used to define a new DLHARQ timing.

i) A new DL HARQ timing may be defined or designed to allow PDSCHtransmission in all DL subframes of an SCell (FDD). This may optimizeperformance of the overall system and a peak data rate of a terminal.

ii) A terminal that supports TDD(PCell)-FDD(SCell) CA may use PUCCHformat 1b with channel selection That is, a channel selection-basedtransmission method that uses PUCCH format 1b format may be configuredfor a terminal, for transmission of HARQ-ACK information on a PUCCHduring a CA.

iii) Since a new DL HARQ timing is added, DL HARQ timing values forindicating DL subframes associated with a single UL subframe may beidentified as a legacy DL HARQ timing value and a new DL HARQ timingvalue. Accordingly, the DL subframes may be distinguished as a DLsubframe associated with a legacy DL HARQ timing (hereinafter, legacyassociated subframe) and a DL subframe associated with a new DL HARQtiming (hereinafter, new associated subframe). Accordingly, a new indexk₀′, k₁′, . . . for indicating a new associated subframe may be added toa DL subframe set K={k₀, k₁, . . . , K_(M-1)} associated with a currentUL subframe.

iv) HARQ ACKs/NACKs may be bundled between a legacy associated subframeand a new associated subframe, based on a ratio of 1:1 or N:1. In thisinstance, a DL assignment index (DAI) for the bundled DL subframes maybe fixed to be identical. According to the above, the number of bitsused for the DAI is maintained, and the number of HARQ-ACK(j) may bemaintained constantly to use the channel selection-based transmissionmethod. Here, HARQ ACK/NACK bundling may include time bundling, spatialbundling, or a combination of time bundling and spatial bundling.

v) HARQ ACK/NACK bundling between a legacy associated subframe and a newassociated subframe may be executed when a PDCCH and/or an EPDCCH thatindicates PDSCH transmission exists in all of the legacy associatedsubframes and the new associated subframe (that is, a case in which aDAI value of 5 exists when M=5). That is, when PDSCH transmission isavailable in all of the legacy associated subframes and all of the newassociated subframes associated with a predetermined UL subframe, a HARQACK/NACK for a PDSCH of a new associated subframe may be bundled with aHARQ ACK/NACK of a PDSCH of at least one legacy associated subframe.

Otherwise, HARQ ACK/NACK bundling may not be executed between a legacyassociated subframe and a new associated subframe. That is, HARQACK/NACK transmission identical to the existing method may be executed.

vi) A HARQ ACK/NACK may be transmitted through PUCCH format 1b based onchannel selection or may be transmitted through a PUSCH based on whetherPUSCH transmission exists. The HARQ ACK/NACK transmission may beexecuted on a PCell or an SCell. However, it is basically understoodthat the HARQ ACK/NACK transmission is executed on the PCell.

FIGS. 10 and 11 are diagrams illustrating a new DL HARQ timing accordingto an embodiment of the present invention. FIG. 10 corresponds to a casein which UL/DL configuration 2 is applied to a PCell, and FIG. 11corresponds to a case in which UL/DL configuration 4 is applied to aPCell.

Referring to FIG. 10, the PCell operates based on TDD, and the UL-DLconfiguration 2 is applied to the PCell. FDD is applied to an SCell. Asubframe set of subframes associated with subframes #2 and #7 is asubframe set K={8, 7, 6, 5, 4}. Among the set, k=8, 7, 4, 6 correspondto legacy DL HARQ timings indicating legacy associated subframes(identical to Table 3), and k=5 corresponds to a new DL HARQ timingindicating a new associated subframe (a modification of Table 3). Thatis, according to the design that further includes the new DL HARQtiming, UL subframes #2 and #7 of the PCell are associated with five DLsubframes, respectively. That is, in a case in which a bundling windowsize M (or the number of k in the set K) defined for the legacyassociated subframes is 4, an event of M>4 may be incurred after a newassociated subframe is added.

Subframes associated with the subframe #2 are DL subframes #4, #5, #6,#7, and #8 of a previous frame, and subframes associated with thesubframe #7 are a DL subframe #9 of the previous frame and DL subframes#0, #1, #2, and #3 of a current frame. Therefore, all of the subframesof the SCell are secured as DL HARQ timings. Here, among the DL HARQtimings, the DL subframes #2 and #7 correspond to new associatedsubframes.

Referring to FIG. 11, the PCell operates based on TDD, and the UL-DLconfiguration 4 is applied to the PCell. FDD is applied to an SCell. Asubframe set of subframes associated with a subframe #2 is subframe setK={12, 11, 10, 8, 7}. Among the set, k=12, 11, 8, 7 correspond to legacyDL HARQ timings indicating legacy associated subframes (identical toTable 3), and k=10 corresponds to a new DL HARQ timing indicating a newassociated subframe (a modification of Table 3). A subframe set ofsubframes associated with a subframe #3 is a subframe set K={10, 7, 6,5, 4}. Among the set, k=7, 6, 5, 4 correspond to legacy DL HARQ timingsindicating legacy associated subframes, and k=10 corresponds to a new DLHARQ timing indicating a new associated subframe.

That is, according to the design that further includes the new DL HARQtiming, UL subframes #2 and #3 of the PCell are associated with five DLsubframes, respectively. That is, in a case in which a bundling windowsize M (or the number of k in the set K) defined for the legacyassociated subframes is 4, an event of M>4 may be incurred after a newassociated subframe is added.

Subframes associated with the subframe #2 are DL subframes #0, #1, #2,#4, and #5 of a previous frame, and subframes associated with thesubframe #3 are DL subframes #3, #6, #7, #8, and #9 of the previousframe. Therefore, all of the subframes of the SCell are secured as DLHARQ timings. Here, among the DL HARQ timings, the DL subframes #2 and#3 correspond to new associated subframes.

When only legacy associated subframes are used, HARQ for PDSCHtransmission may not be supported in a few DL subframes of the SCell.Therefore, as illustrated in FIGS. 10 and 11, a new associated subframeis for a DL subframe that is not supportable through the existing TDDUL-DL configuration, and thereby, HARQ for PDSCH transmission may besupported in all of the DL subframes of the SCell.

Accordingly, new associated subframes may be added to the set Kassociated with a single UL subframe. This may indicate that anadditional HARQ ACK/NACK for the new associated subframe needs to betransmitted. To this end, the bundling window size M needs to beincreased or a DAI with an increased number of bits (for example, 3 bitsfor a DAI) may be used, so as to add a HARQ ACK/NACK. However, anoverhead may be incurred in a PDCCH from a perspective of a DL and anoverhead in resources for an additional HARQ ACK/NACK may be caused froma perspective of a UL. Therefore, there is a desire for a method oftransmitting an additional HARQ ACK/NACK for a new associated subframe,without a change in the existing communication protocol.

The present embodiment provides a method of bundling a HARQ ACK/NACKwith respect to a new associated subframe (hereinafter new HARQACK/NACK) and a HARQ ACK/NACK with respect to a legacy associatedsubframe (hereinafter legacy HARQ ACK/NACK). To this end, which of thelegacy HARQ ACK/NACKs is to be bundled with a new HARQ ACK/NACK and howthe bundling is executed may need to be defined, that is, a bundlingmethod needs to be defined. In addition, a method of setting a DAI valuefor a new associated subframe may need to be defined. The definitionshould be made to provide minimum effect on the existing standards.

FIG. 12 is a diagram illustrating a legacy HARQ ACK/NACK that may bebundled with a new HARQ ACK/NACK according to an embodiment of thepresent invention. This is a case in which PUCCH format 1b with channelselection is configured for a terminal, for transmission of a HARQACK/NACK.

Referring to FIG. 12, legacy associated subframes are subframes n−8,n−7, n−6, and n−4, and a new associated subframe is a subframe n−5.Here, a radio of bundling between a legacy associated subframe and a newassociated subframe is 1:1. That is, a single new HARQ ACK/NACK and asingle legacy HARQ ACK/NACK are bundled. As a matter of course, a ratioof bundling between a legacy associated subframe and a new associatedsubframe may be N:1 or 1:N. By the following various options, a legacyHARQ ACK/NACK to be bundled with the new HARQ ACK/NACK may be selected.

For example, according to option 1, a HARQ ACK/NACK of the subframe n−5(new HARQ ACK/NACK) and a HARQ ACK/NACK of the subframe n−6 (legacy HARQACK/NACK) may be bundled. That is, the new HARQ ACK/NACK is bundled witha HARQ ACK/NACK of an immediately previous legacy associated subframe.

As another example, according to option 2, the HARQ ACK/NACK of thesubframe n−5 (new HARQ ACK/NACK) and a HARQ ACK/NACK of the subframe n−4(legacy HARQ ACK/NACK) may be bundled. That is, the new HARQ ACK/NACK isbundled with a HARQ ACK/NACK of an immediately subsequent legacyassociated subframe.

As another example, according to option 3, the HARQ ACK/NACK of thesubframe n−5 (new HARQ ACK/NACK) and a HARQ ACK/NACK of the subframe n−7(legacy HARQ ACK/NACK) may be bundled. That is, the new HARQ ACK/NACK isbundled with a HARQ ACK/NACK of a legacy associated subframe, which istwo legacy associated subframes before from the new associated subframe.

As another example, according to option 4, the HARQ ACK/NACK of thesubframe n−5 (new HARQ ACK/NACK) and a HARQ ACK/NACK of the subframe n−8(legacy HARQ ACK/NACK) may be bundled. That is, the new HARQ ACK/NACK isbundled with a HARQ ACK/NACK of a legacy associated subframe, which isthree legacy associated subframes before from the new associatedsubframe.

According to the various options, a terminal executes bundling of a HARQACK/NACK of one of the legacy DL subframes in the subframe set Kassociated with an identical UL subframe and a new HARQ ACK/NACK, so asto generate a HARQ ACK/NACK of 1 bit. Hereinafter, a HARQ ACK/NACKbundling method will be described.

In FIG. 12, it is defined that the HARQ ACK/NACK bundling is executedbetween subframes having fixed indices, based on four options. However,the HARQ ACK/NACK bundling may be defined based on a DAI value, as shownin FIG. 13.

Referring to FIG. 13, HARQ ACK/NACK bundling may be executed between alatest DL subframe having a DAI value of 4 and a latest DL subframehaving a DAI value of 5 from among DAI values (V^(DL) _(ΔAI,χ)) in a DLDCI format transmitted in each subframe of the associated subframe set Kon a serving cell c. That is, HARQ ACK/NACK bundling may be executedbetween DL subframes selected based on a DAI value. In this instance,M=5 and thus, it is substantially the same as option 2 of FIG. 12, fromthe perspective of HARQ ACK/NACK bundling.

FIG. 14 is a diagram illustrating HARQ ACK/NACK bundling according to anembodiment of the present invention.

Referring to FIG. 14, under an assumption of a mode that enables a basestation to transmit two TBs in a single subframe, when PDSCHtransmission is indicated for two subframes, for HARQ-ACK transmissionfor the PDSCH transmission, HARQ ACK/NACK bundling may be executed asfollows.

i) When PDSCH transmission is executed in both a legacy DL subframe anda new associated subframe, a terminal executes time bundling first withrespect to each codeword over two subframes, and executes spatialbundling. For example, the terminal executes bundling of a HARQ ACK/NACKwith respect to a codeword 0 (CW0) of a legacy DL subframe and a HARQACK/NACK with respect to a codeword 0 (CW0) of a new DL subframe, so asto obtain a first time bundled HARQ ACK/NACK, executes bundling of aHARQ ACK/NACK with respect to a codeword 1 (CW1) of a legacy DL subframeand a HARQ ACK/NACK with respect to a codeword 1 (CW1) of a new DLsubframe, so as to obtain a second time bundled HARQ ACK/NACK, andexecutes bundling of the first time bundled HARQ ACK/NACK and the secondtime bundled HARQ ACK/NACK, so as to generate a HARQ-ACK(j), which is afinal bundled HARQ ACK/NACK. Here, j is identical to a DAI or a DAI-1.

ii) When PDSCH transmission is executed in only one of a legacy DLsubframe and a new associated subframe, a terminal executes only thespatial bundling. For example, when PDSCH transmission is executed onlyin the new associated subframe, the terminal executes bundling of a HARQACK/NACK with respect to a codeword 0 (CW0) and a HARQ ACK/NACK withrespect to a codeword 1 (CW1) of the new DL subframe, so as to generatea HARQ-ACK(j), which is a final bundled HARQ ACK/NACK.

In a mode that allows a base station to transmit a single TB in a singlesubframe, HARQ ACK/NACK bundling may be executed as follows.

i) When PDSCH transmission is executed in both a legacy DL subframe anda new associated subframe, a terminal executes only time bundling withrespect to each codeword over two subframes. For example, when it isassumed that only a codeword 0 is transmitted, the terminal executesbundling of a HARQ ACK/NACK with respect to a codeword 0 (CW0) of thelegacy DL subframe and a HARQ ACK/NACK with respect to a codeword 0(CW0) of the new DL subframe, so as to generate a HARQ-ACK(j), which isa final bundled HARQ ACK/NACK.

ii) When PDSCH transmission is executed in only one of the legacy DLsubframe and the new associated subframe, the terminal does not executeany bundling.

FIG. 15 is a diagram illustrating HARQ ACK/NACK bundling according toanother embodiment of the present invention.

Referring to FIG. 15, in a mode that allows a base station to transmittwo TBs in a single subframe, HARQ ACK/NACK bundling may be executed asfollows.

i) When PDSCH transmission is executed in both a legacy DL subframe anda new associated subframe, a terminal executes spatial bundling firstwith respect to each codeword over two subframes, and executes timebundling. For example, the terminal executes bundling of a HARQ ACK/NACKwith respect to a codeword 0 (CW0) of the legacy DL subframe and a HARQACK/NACK with respect to a codeword 1 (CW1) of the legacy DL subframe,so as to obtain a first spatial bundled HARQ ACK/NACK, executes bundlingof a HARQ ACK/NACK of a codeword 0 (CW0) of the new DL subframe and aHARQ ACK/NACK of a codeword 1 (CW1) of the new DL subframe, so as toobtain a second spatial bundled HARQ ACK/NACK, and executes bundling ofthe first spatial bundled HARQ ACK/NACK and the second spatial bundledHARQ ACK/NACK, so as to generate a HARQ-ACK(j), which is a final bundledHARQ ACK/NACK. Here, j is identical to a DAI or a DAI-1.

ii) When PDSCH transmission is executed in only one of a legacy DLsubframe and a new associated subframe, a terminal executes only thespatial bundling. For example, when PDSCH transmission is executed onlyin the new associated subframe, the terminal executes bundling of a HARQACK/NACK with respect to a codeword 0 (CW0) and a HARQ ACK/NACK withrespect to a codeword 1 (CW1) of the new DL subframe, so as to generatea HARQ-ACK(j), which is a final bundled HARQ ACK/NACK.

FIG. 16 is a diagram illustrating HARQ ACK/NACK bundling according toanother embodiment of the present invention.

Referring to FIG. 16, in a mode that allows a base station to transmit asingle TB in a single subframe, HARQ ACK/NACK bundling may be executedas follows.

i) When PDSCH transmission is executed in both a legacy DL subframe anda new associated subframe, a terminal executes only time bundling withrespect to each codeword over two subframes. For example, when it isassumed that only a codeword 0 is transmitted, the terminal executesbundling of a HARQ ACK/NACK with respect to a codeword 0 (CW0) of thelegacy DL subframe and a HARQ ACK/NACK with respect to a codeword 0(CW0) of the new DL subframe, so as to generate a HARQ-ACK(j), which isa final bundled HARQ ACK/NACK.

ii) When PDSCH transmission is executed in only one of the legacy DLsubframe and the new associated subframe, the terminal does not executeany bundling.

The present specification discloses a method of optionally using PUCCHformat 3 in addition to the bundling method of FIGS. 14 through 16, fortransmission of a new HARQ ACK/NACK.

According to an embodiment, for transmission of a new HARQ ACK/NACK withrespect to a PDSCH of an SCell that operates based on FDD in a TDD-FDDCA, PUCCH format 1b with channel selection is used when a bundlingwindow size M is less than or equal to 4, and PUCCH format 3 may be usedwhen M is greater than 4. That is, under the condition of M>4, PUCCHformat 1b with channel selection may not be configured for theTDD(PCell)-FDD(SCell) CA terminal, or may be automatically changed intoPUCCH format 3 although it is configured for the TDD(PCell)-FDD(SCell)CA terminal.

Hereinafter, a method of setting a DAI value for a new associatedsubframe will be defined.

When the bundling window size M is changed, the transmission methodusing PUCCH format 1b with channel selection may need to be changed. Tominimize an effect on the existing transmission method using PUCCHformat 1b, the present embodiment provides a method of using a channelselection table without changing the value of M although a newassociated subframe is added.

As an example, a DAI value of a new associated subframe is identical toa DAI value of at least one legacy associated subframe, as shown in FIG.17. A terminal and a base station should recognize that the identicalDAI value is used for two or more associated subframes. According to theexample, the DAI value may be accumulatively increased according to thenumber of PDCCHs and/or EPDCCHs that indicate PDSCH transmission.However, exceptionally, a DAI for the new associated subframe may not beaccumulatively increased, and uses a DAI value of one of the legacyassociated subframes. In this instance, since the case of M=5 comes froma new DL HARQ timing, the terminal may execute HARQ ACK/NACK bundling,by unifying a DAI and regarding the two subframes as a single virtualsubframe.

As another example, a DAI value of a new associated subframe isdifferent from a DAI value of a legacy associated subframe. According tothe example, a DAI value has a value accumulated according to the numberof PDCCHs and/or EPDCCHs indicating PDSCH transmission, and there is noexception for a DAI of the new associated subframe. This is to remove aneffect on a method of transmitting a HARQ ACK/NACK using a DAI value ona PUSCH. That is, for UL-DL configurations 1 through 6, a DAI value in aDCI format may be updated for each subframe (from subframe to subframe).A terminal according to the present specification may support a case inwhich all of the ten subframes of an SCell are associated with a singleUL subframe (that is, a new DL HARQ timing) and thus, a DAI value shouldindicate a maximum of ten subframes having a PDSCH. According to theabove, the DAI value may be defined as shown in Table 5.

TABLE 5 Number of subframes having DAI PDSCH and number of subframesMSB, V^(UL) _(DAI) or having PDCCH/EPDCCH LSB V^(DL) _(DAI) indicatingDL SPS release 0, 0 1 1 or 5 or 9 0, 1 2 2 or 6 or 10 1, 0 3 3 or 7 1, 14 0 or 4 or 8

Referring to Table 5, a DAI has 2 bits, and is formed of an MSB and anLSB. In a case in which MSB=0 and LSB=1 (that is, when a DAI value is2), the number of subframes having a PDSCH and the number of subframeshaving a PDCCH/EPDCCH indicating DL SPS release may be 2, 6, or up to10. That is, the DAI value may cover PDSCH allocation of ten subframes.In this instance, only when M=5 and DAI=5, the terminal executes HARQACK/NACK bundling, and a HARQ-ACK(j) index for the bundled HARQ ACK/NACKmay be HARQ-ACK(3) corresponding to a DAI=4.

FIG. 18 is a flowchart illustrating a HARQ ACK/NACK transmission methodaccording to an embodiment of the present invention.

Referring to FIG. 18, a base station transmits data over a PCell or anSCell configured for a terminal, in operation S1800. Accordingly, theterminal receives the data transmitted over the PCell or the SCell. ThePCell may operate based on a TDD mode, and the SCell may operate basedon an FDD mode. The data may be referred to as a TB or a codeword, and aplurality of TBs (or codewords) may be transmitted over a singlesubframe (please see FIGS. 14 and 15). The data may be mapped to a PDSCHfor transmission. Together with the data, a PDCCH or an EPDCCHindicating the data may be transmitted. A DCI including a DAI value maybe mapped to the PDCCH. A DAI value associated with a new associatedsubframe, as disclosed in the present specification, may or may not beidentical to a DAI value of at least one legacy associated subframe. Thedata may be transmitted over a plurality of subframes. The plurality ofsubframes may include a plurality of legacy associated subframes and atleast one new associated subframe.

For example, the base station transmits a first TB in a first subframeof the SCell, transmits a second TB in a second subframe of the SCell,and transmits a third TB in a third subframe of the SCell. However, theplurality of subframes may not need to be consecutive subframes.

The terminal generates a HARQ-ACK(j) with respect to the received datain operation S1805. The HARQ-ACK(j) may be separately generated for eachof the PCell and the SCell, and for each DAI. Each HARQ-ACK(j) may beindexed based on a DAI value.

First, a method of generating a HARQ-ACK (j) in the PCell will bedescribed. In a case in which the UL-DL configuration of the PCellcorresponds to UL-DL configuration 1, 2, 3, 4, 5, or 6, and 0≦j≦M−1,when a PDCCH and/or EPDCCH of an associated subframe and PDSCHtransmission exist in the PCell, and a DAI value in the PDCCH and/orEPDCCH is j+1, the terminal generates a HARQ-ACK(j) indicating ACK,NACK, or DTX with respect to data in each associated subframe. In a casein which 0≦j≦M−1 and the UL-DL configuration of the PCell corresponds toUL-DL configuration 0, when a PDCCH and/or EPDCCH of an associatedsubframe and PDSCH transmission exist, the terminal sets the HARQ-ACK(0)as ACK, NACK, or DTX with respect to corresponding data, and for therest, the terminal sets HARQ-ACK(j) as DTX.

Subsequently, a method of generating a HARQ-ACK (j) in the SCell will bedescribed. In a case of 0≦j≦M−1, when a PDCCH and/or EPDCCH of anassociated subframe and PDSCH transmission exist in the SCell, and a DAIvalue in the PDCCH and/or EPDCCH is j+1, the terminal generates aHARQ-ACK(j) indicating ACK, NACK, or DTX with respect to data in eachassociated subframe.

The terminal generates HARQ-ACK(0), HARQ-ACK(1), . . . which are indexedby a DAI value, with respect to data received through associatedsubframes of the PCell, and generates HARQ-ACK(0), HARQ-ACK(1), . . .which are indexed by a DAI value, with respect to data received throughassociated subframes of the SCell. For example, a combination of fourHARQ-ACK(j)s may exist in the PCell, and a combination of fourHARQ-ACK(j)s may exist in the SCell. A combination of eight HARQ-ACK(j)smay be transmitted through a single UL subframe. Throughout the presentspecification, in the expression “a HARQ ACK/NACK is transmitted througha single UL subframe”, the “HARQ ACK/NACK” may refer to a combinationsof a plurality of HARQ-ACK(j)s.

Here, the terminal may execute HARQ ACK/NACK bundling based on one ofthe all embodiments disclosed in the present specification. That is,when M=5 and DAI=5 on the SCell, an HARQ-ACK(j) indexed by a DAIassociated with a new associated subframe may be bundled with aHARQ-ACK(j′) of at least one legacy associated subframe. For example, aHARQ-ACK(3) corresponds to a DAI value of 4, which is a result ofbundling between a HARQ ACK/NACK with respect to a PDSCH of a legacyassociated subframe having a DAI=4 and a HARQ ACK/NACK with respect to aPDSCH of a new associated subframe having a DAI=5.

The terminal transmits the HARQ ACK/NACK to the base station in apredetermined UL subframe, in operation S1810. The HARQ ACK/NACK may betransmitted through PUCCH format 1b with channel selection, or may betransmitted on a PUSCH.

As an example, the terminal may transmit the HARQ ACK/NACK to the basestation using a PUCCH resource index n⁽¹⁾ _(ΠYXXH,ι) and a modulationsymbol, corresponding to the HARQ-ACK(j). When M=5 and DAI=5 exists onthe SCell, a channel selection table to which the HARQ-ACK(j) and PUCCHresource index/modulation symbol are mapped, may be used. An example ofthe channel selection table may be as shown in Table 6.

TABLE 6 RM code PCell SCell resource constellation input bitsHARQ-ACK(0), HARQ- HARQ-ACK(0), HARQ- n⁽¹⁾ _(PUCCH) b(0), b(1) o(0),o(1), ACK(1), ACK( 1 ), HARQ- o(2), (3) HARQ-ACK(2), HARQ- ACK(2),HARQ-ACK(3) ACK(3) ACK, ACK, ACK, ACK, ACK, ACK, n⁽¹⁾ _(PUCCH,1) 1, 1 1,1, 1, 1 NACK/DTX NACK/DTX ACK, ACK, ACK, ACK, ACK, n⁽¹⁾ _(PUCCH,1) 0, 01, 0, 1, 1 NACK/DTX, any NACK/DTX ACK, ACK, ACK, ACK, DTX, DTX, DTXNACK/DTX n⁽¹⁾ _(PUCCH,3) 1, 1 0, 1, 1, 1 ACK, ACK, ACK, ACK ACK, ACK,ACK, n⁽¹⁾ _(PUCCH,3) 1, 1 0, 1, 1, 1 NACK/DTX NACK/DTX, any, any, ACK,ACK, ACK, n⁽¹⁾ _(PUCCH,3) 0, 1 0, 0, 1, 1 any NACK/DTX (ACK, NACK/DTX,any, ACK, ACK, ACK, n⁽¹⁾ _(PUCCH,3) 0, 1 0, 0, 1, 1 any), except for(ACK, NACK/DTX DTX, DTX, DTX) ACK, ACK, ACK, ACK, ACK, n⁽¹⁾ _(PUCCH,0)1, 0 1, 1, 1, 0 NACK/DTX NACK/DTX, any ACK, ACK, ACK, ACK, n⁽¹⁾_(PUCCH,3) 1, 0 1, 0, 1, 0 NACK/DTX, any NACK/DTX, any ACK, DTX, DTX,DTX ACK, ACK, n⁽¹⁾ _(PUCCH,0) 0, 1 0, 1, 1, 0 NACK/DTX, any ACK, ACK,ACK, ACK ACK, ACK, n⁽¹⁾ _(PUCCH,0) 0, 1 0, 1, 1, 0 NACK/DTX, anyNACK/DTX, any, any, ACK, ACK, n⁽¹⁾ _(PUCCH,3) 0, 0 0, 0, 1, 0 anyNACK/DTX, any (ACK, NACK/DTX, any, ACK, ACK, n⁽¹⁾ _(PUCCH,3) 0, 0 0, 0,1, 0 any), except for (ACK, NACK/DTX, any DTX, DTX, DTX) ACK, ACK, ACK,ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 1, 1 1, 1, 0, 1 NACK/DTX ACK, ACK,ACK, ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 1, 1 1, 1, 0, 1 NACK/DTX ACK,ACK, ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 0, 1 1, 0, 0, 1 NACK/DTX, anyACK, ACK, ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 0, 1 1, 0, 0, 1 NACK/DTX,any ACK, DTX, DTX, DTX ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 1, 0 0, 1, 0,1 ACK, DTX, DTX, DTX ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 1, 0 0, 1, 0, 1ACK, ACK, ACK, ACK ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 1, 0 0, 1, 0, 1ACK, ACK, ACK, ACK ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 1, 0 0, 1, 0, 1NACK/DTX, any, any, ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 0, 0 0, 0, 0, 1any NACK/DTX, any, any, ACK, ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 0, 0 0, 0, 0,1 any (ACK, NACK/DTX, any, ACK, DTX, DTX, DTX n⁽¹⁾ _(PUCCH,2) 0, 0 0, 0,0, 1 any), except for (ACK, DTX, DTX, DTX) (ACK, NACK/DTX, any, ACK,ACK, ACK, ACK n⁽¹⁾ _(PUCCH,2) 0, 0 0, 0, 0, 1 any), except for (ACK,DTX, DTX, DTX) ACK, ACK, ACK, NACK/DTX, any, any, n⁽¹⁾ _(PUCCH,1) 1, 01, 1, 0, 0 NACK/DTX any ACK, ACK, ACK, (ACK, NACK/DTX, any, n⁽¹⁾_(PUCCH,1) 1, 0 1, 1, 0, 0 NACK/DTX any), except for (ACK, DTX, DTX,DTX) ACK, ACK, NACK/DTX, any, any, n⁽¹⁾ _(PUCCH,1) 0, 1 1, 0, 0, 0NACK/DTX, any any ACK, ACK, (ACK, NACK/DTX, any, n⁽¹⁾ _(PUCCH,1) 0, 1 1,0, 0, 0 NACK/DTX, any any), except for (ACK, DTX, DTX, DTX) ACK, DTX,DTX, DTX NACK/DTX, any, any, n⁽¹⁾ _(PUCCH,0) 1, 1 0, 1, 0, 0 any ACK,DTX, DTX, DTX (ACK, NACK/DTX, any, n⁽¹⁾ _(PUCCH,0) 1, 1 0, 1, 0, 0 any),except for (ACK, DTX, DTX, DTX) ACK, ACK, ACK, ACK NACK/DTX, any, any,n⁽¹⁾ _(PUCCH,0) 1, 1 0, 1, 0, 0 any ACK, ACK, ACK, ACK (ACK, NACK/DTX,any, n⁽¹⁾ _(PUCCH,0) 1, 1 0, 1, 0, 0 any), except for (ACK, DTX, DTX,DTX) NACK, any, any, any NACK/DTX, any, any, n⁽¹⁾ _(PUCCH,0) 0, 0 0, 0,0, 0 any NACK, any, any, any (ACK, NACK/DTX, any, n⁽¹⁾ _(PUCCH,0) 0, 00, 0, 0, 0 any), except for (ACK, DTX, DTX, DTX) (ACK, NACK/DTX, any,NACK/DTX, any, any, n⁽¹⁾ _(PUCCH,0) 0, 0 0, 0, 0, 0 any), except for(ACK, any DTX, DTX, DTX) (ACK, NACK/DTX, any, (ACK, NACK/DTX, any, n⁽¹⁾_(PUCCH,0) 0, 0 0, 0, 0, 0 any), except for (ACK, any), except for (ACK,DTX, DTX, DTX) DTX, DTX, DTX) DTX, any, any, any NACK/DTX, any, any, NoTransmission 0, 0, 0, 0 any DTX, any, any, any (ACK, NACK/DTX, any, NoTransmission 0, 0, 0, 0 any), except for (ACK, DTX, DTX, DTX)

Referring to Table 6, a combination of four HARQ-ACK(j)s exists in thePCell, and a combination of four HARQ-ACK(j)s exists in the SCell. Acombination of eight HARQ-ACK(j)s is mapped to an actual physicalresource for transmission, a combination of HARQ-ACK(j)s may beindicated by a constellation of a PUCCH resource index, which is anactual physical resource, and a modulation symbol.

For example, when HARQ-ACK(j)={ACK, ACK, ACK, NACK/DTX} in the PCell andHARQ-ACK(j)={ACK, ACK, ACK, NACK/DTX} in the SCell, a combination of theHARQ-ACK(j)s may be mapped to n⁽¹⁾ _(ΠYXXH,1) and modulation symbolconstellation (1,1). For example, a HARQ-ACK(3) in the SCell correspondsto a DAI value of 4, which is a result of bundling between a HARQACK/NACK with respect to a PDSCH of a legacy associated subframe havinga DAI=4 and a HARQ ACK/NACK with respect to a PDSCH of a new associatedsubframe having a DAI=5.

The resource index n^((l)) _(ΠYXXH,ι), which is a resource for PUCCHformat 1/1a/1b transmission, may be used for determining a Cyclic Shift(CS) amount α(n_(σ)1) of a base sequence and an orthogonal sequenceindex n_(OX)(n_(σ)), in addition to a location of the physical resourcethrough which a HARQ ACK/NACK signal is transmitted. Control informationtransmitted on a PUCCH may use a cyclically shifted sequence, and thecyclic shift sequence is obtained by cyclically shifting a base sequenceby a predetermined CS amount.

For example, the resource index n⁽¹⁾ _(ΠYXXH,ι) may be obtained as shownin Table 7. The resource index n⁽¹⁾ _(ΠYXXH,ι) is a parameter thatdetermines a physical RB index n_(ΠPB), a CS amount α(n_(σ),1) of a basesequence, an orthogonal sequence index n_(OX)(n_(σ)), and the like.

TABLE 7 dynamic scheduling Semi-static scheduling Resource index n⁽¹⁾_(PUCCH,i) = (M_(primary)-m- Signaling through higher 1)N_(c) +mN_(c + 1) + n_(CCE,M) + layer or control channel N⁽¹⁾ _(PUCCH) Upperlayer n⁽¹⁾ _(PUCCH) n⁽¹⁾ _(PUCCH) Signaling value

Referring to Table 7, c is one of 0, 1, 2, and 3, andN_(χ)≦n_(XXE,M)≦N_(X+1). Also, N_(χ)=max{0, └[N_(RB) ^(DL)·(N_(sc)^(RB)·c−4)]/36┘}. i is a parameter that is determined dependently, basedon a DAI value, and may have 0, 1, 2, and 3. According to the above, aHARQ ACK/NACK signal with respect to a PDSCH transmitted in a n^(th)subframe, may be calculated based on a function of a first ControlChannel Element (CCE) index n_(XXE,M) of a PDCCH transmitted in an−k^(th) subframe and N⁽¹⁾ _(ΠYXXH) obtained through a higher layersignaling or a separate control channel.

From the perspective of a physical resource, a Reference Signal (RS) iscontained in three SC-FDMA symbols of seven SC-FDMAs, and a HARQACK/NACK signal is contained in the remaining four SC-FDMA symbols. TheRS may be included in the three contiguous SC-FDMA symbols in the middleof a slot.

FIG. 19 illustrates an example of mapping a PUCCH to physical RBs.

Referring to FIG. 19, a physical RB index n_(ΠPB) is determined based ona resource index n⁽¹⁾ _(ΠYXXH,ι), and a PUCCH corresponding to each mmay execute frequency hopping based on a slot unit.

A PUCCH format that transmits a HARQ ACK/NACK signal may include PUCCHformat 1a/1b that use channel selection and PUCCH format 3. The PUCCHformat 1a/1b with channel selection may transmit a HARQ ACK/NACK signalof 2 to 4 bits. PUCCH format 3 may transmit a HARQ ACK/NACK signal of upto 20 bits for TDD, and a HARQ ACK/NACK signal of up to 10 bits for FDD.

Referring again to FIG. 18, as another example, the terminal maytransmit a HARQ ACK/NACK to a base station through a PUSCH, using an RMcode input bit corresponding to a HARQ-ACK(j). In this instance, whenthe HARQ ACK/NACK is transmitted through the PUSCH, PUCCH format 1/1a/1bwith channel selection or PUCCH format 3 may need to be configured forthe terminal, and PUSCH transmission needs to be scheduled on acorresponding UL subframe. When M=4 or 5, o_(φ) ^(ACK)=o(j) isdetermined with reference to the channel selection table of Table 6corresponding to M=4. For example, when HARQ-ACK(j)={ACK, ACK, ACK,NACK/DTX} in the PCell and HARQ-ACK(j)={ACK, ACK, ACK, NACK/DTX} in theSCell, a combination of the HARQ-ACK(j)s may be mapped to RM code inputbit o(j)={1,1,1,1}.

FIG. 20 is a block diagram illustrating a terminal and a base stationaccording to an embodiment of the present invention.

Referring to FIG. 20, a terminal 2000 includes a receiving unit 2005, aterminal processor 2010, and a transmitting unit 2015. The receivingunit 2005 receives data transmitted from a base station 2050 over aPCell or an SCell. Here, the data is referred to as a TB or a codeword.The data is received through a PDSCH. Together with the data, a PDCCH oran EPDCCH indicating the data may be transmitted. Here, a DCI includinga DAI may be mapped to the PDCCH. A DAI value associated with a newassociated subframe, as disclosed in the present specification, may ormay not be identical to a DAI value of at least one legacy associatedsubframe. The PCell may operate based on a TDD mode, and the SCell mayoperate based on an FDD mode.

The receiving unit 2005 may receive the data over a plurality ofsubframes. The plurality of subframes may include a plurality of legacyassociated subframes and at least one new associated subframe. Forexample, the receiving unit 2005 receives a first TB in a first subframeof the SCell, receives a second TB in a second subframe of the SCell,and receives a third TB in a third subframe of the SCell. However, theplurality of subframes may not need to be consecutive subframes.

The terminal processor 2010 generates a HARQ-ACK(j) with respect to thereceived data. The terminal processor 2010 may execute a MAC layerprocedure associated with HARQ. The terminal processor 2010 mayseparately generate a HARQ-ACK(j) for each of the PCell and the SCell,and for each DAI.

In a case in which the UL-DL configuration of the PCell corresponds toUL-DL configuration 1, 2, 3, 4, 5, or 6, and 0≦j≦M−1, when a PDCCHand/or EPDCCH of an associated subframe and PDSCH transmission exist inthe PCell, and a DAI value in the PDCCH and/or EPDCCH is j+1, theterminal processor 2010 generates a HARQ-ACK(j) indicating ACK, NACK, orDTX with respect to data in each associated subframe. In a case in which0≦j≦M−1 and the UL-DL configuration of the PCell corresponds to UL-DLconfiguration 0, when a PDCCH and/or EPDCCH of an associated subframeand PDSCH transmission exist, the terminal processor 2010 sets aHARQ-ACK(0) as ACK, NACK, or DTX with respect to corresponding data, andfor the rest, the terminal processor 2010 sets a HARQ-ACK(j) as DTX.

In a case of 0≦j≦M−1, when a PDCCH and/or EPDCCH of an associatedsubframe and PDSCH transmission exist in the SCell, and a DAI value inthe PDCCH and/or EPDCCH is j+1, the terminal processor 2010 generates aHARQ-ACK(j) indicating ACK, NACK, or DTX with respect to data in eachassociated subframe.

The terminal processor 2010 generates HARQ-ACK(0), HARQ-ACK(1), . . .which are indexed by a DAI value, with respect to data received throughassociated subframes of the PCell, and generates HARQ-ACK(0),HARQ-ACK(1), . . . which are indexed by a DAI value, with respect todata received through associated subframes of the SCell. For example, acombination of four HARQ-ACK(j)s may exist in the PCell, and acombination of four HARQ-ACK(j)s may be generated in the SCell.

Here, the terminal processor 2010 may execute HARQ ACK/NACK bundlingbased on one of the all embodiments disclosed in the presentspecification. That is, when M=5 and DAI=5 on the SCell, an HARQ-ACK(j)indexed by a DAI associated with a new associated subframe may bebundled with a HARQ-ACK(j′) of at least one legacy associated subframe.For example, a HARQ-ACK(3) corresponds to a DAI value of 4, which is aresult of bundling between a HARQ ACK/NACK with respect to a PDSCH of alegacy associated subframe having a DAI=4 and a HARQ ACK/NACK withrespect to a PDSCH of a new associated subframe having a DAI=5.

The transmitting unit 2015 transmits a HARQ ACK/NACK generated by theterminal processor 2010 to the base station 2050 using a predeterminedUL subframe and predetermined resource. The transmitting unit 2015 maytransmit the HARQ ACK/NACK through PUCCH format 1b with channelselection, or on a PUSCH.

When the transmitting unit 2015 transmits the HARQ ACK/NACK using PUCCHformat 1b with channel selection, the channel selection table of Table 6may be used.

The base station 2050 includes a transmitting unit 2055, a receivingunit 2060, and a base station processor 2065.

The transmitting unit 2055 transmits data to the terminal 2000 over aPCell or an SCell. Here, the data is referred to as a TB or a codeword.The data is received through a PDSCH. Together with the data, a PDCCH oran EPDCCH indicating the data may be received. Here, a DCI including aDAI may be mapped to the PDCCH, and the DCI may be generated by the basestation processor 2065. A DAI value associated with a new associatedsubframe, as disclosed in the present specification, may or may not beidentical to a DAI value of at least one legacy associated subframe.

The base station processor 2065 calculates a DAI value having a valueaccumulated according to the number of PDCCHs and/or EPDCCHs indicatingPDSCH transmission. In this instance, there is no exception for a DAI ofa new associated subframe. For UL-DL configurations 1 through 6, thebase station processor 2065 updates a DAI value in a DCI format for eachsubframe (from subframe to subframe). The terminal 2000 according to thepresent specification may support a case in which all of the tensubframes of the SCell are associated with a single UL subframe (thatis, a new DL HARQ timing), the base station processor 2065 may configurea DAI value to indicate a cumulative number of transmitted PDSCHs, thatis, up to ten subframes having a PDSCH.

The receiving unit 2060 receives a HARQ ACK/NACK that is transmittedthrough a predetermined UL subframe and resource. The receiving unit2060 may receive the HARQ ACK/NACK through PUCCH format 1b with channelselection, or on a PUSCH. In this instance, when the HARQ ACK/NACK istransmitted through the PUSCH, PUCCH format 1/1a/1b with channelselection or PUCCH format 3 may need to be configured for the terminal,and PUSCH transmission needs to be scheduled on a corresponding ULsubframe.

When the receiving unit 2060 receives the HARQ ACK/NACK using PUCCHformat 1b with channel selection, the channel selection table of Table 6may be used.

The above description is to explain the technical aspects of exemplaryembodiments of the present invention, and it will be apparent to thoseskills in the art that modifications and variations can be made withoutdeparting from the spirit and scope of the present invention. Thus, itis intended that the present invention cover the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed is:
 1. A method of communicating control informationbetween a base station and a user equipment (UE), the method comprising:establishing a Radio Resource Control (RRC) connection with the basestation through a first serving cell, the first serving cell supportinga Time Division Duplex (TDD) mode; receiving an RRC message from thebase station through the first serving cell, the RRC message comprisingcarrier aggregation (CA) configuration information, the CA configurationinformation comprising information of a second serving cell supporting aFrequency Division Duplex (FDD) mode, and the first serving cell and thesecond serving cell being aggregated by a TDD-FDD CA scheme; checking a2-bit downlink (DL) downlink assignment index (DAI) field configured ina DL downlink control information (DCI) format, the DL DCI formatindicating a Physical Downlink Shared Channel (PDSCH) transmission onthe second serving cell, and the 2-bit DL DAI field indicating that tendownlink subframes for the second serving cell are associated with auplink subframe; receiving, at the UE, at least one of a PhysicalDownlink Control Channel (PDCCH) and an Enhanced PDCCH (EPDCCH), the atleast one of the PDCCH and the EPDCCH comprising the DL DCI format;receiving, at the UE, data through the first serving cell and the secondserving cell; in response to the received data, generating a HybridAutomatic Repeat reQuest (HARQ) Acknowledgement/Negative Acknowledgement(ACK/NACK) signal, the HARQ ACK/NACK signal being indexed based on avalue of the 2-bit DL DAI field; and transmitting the HARQ ACK/NACKsignal through the uplink subframe of the first serving cell.
 2. Themethod of claim 1, further comprising: checking a 2-bit uplink (UL) DAIfield configured in a UL DCI format, the UL DCI format indicating aPhysical Uplink Shared Channel (PUSCH) transmission on the secondserving cell.
 3. The method of claim 1, wherein, if the value of the2-bit DL DAI field corresponds to 2, the value of the 2-bit DL DAI fieldindicates that at least one of the number of subframes with the PDSCHtransmission and the number of subframes with the PDCCH or the EPDCCHindicating DL Semi-Persistent Scheduling (SPS) release is 2, 6, or 10.4. The method of claim 1, further comprising: checking that a value of amost significant bit (MSB) of the 2-bit DL DAI field is zero (0) and avalue of a least significant bit (LSB) of the 2-bit DL DAI field is one(1).
 5. The method of claim 1, wherein the 2-bit DL DAI field is definedin the following Table: Number of subframes having PDSCH and DAI numberof subframes having MSB, V^(UL) _(DAI) or PDCCH/EPDCCH indicating DLSemi- LSB V^(DL) _(DAI) Persistent Scheduling (SPS) release 0, 0 1 1 or5 or 9 0, 1 2 2 or 6 or 10 1, 0 3 3 or 7 1, 1 4 0 or 4 or 8 wherein theMSB is a most significant bit, the LSB is a least significant bit,V^(UL) _(DAI) denotes a value of a UL DAI field, and V^(DL) _(DAI)denotes the value of the DL DAI field.


6. The method of claim 1, wherein generating of the HARQ ACK/NACK signalcomprising: generating first HARQ ACK/NACKs indexed based on the valueof the 2-bit DL DAI field, the first HARQ ACK/NACKs being responsive tothe data received through subframes of the first serving cell;generating second HARQ ACK/NACKs indexed based on the value of the 2-bitDL DAI field, the second HARQ ACK/NACKs being responsive to the datareceived through subframes of the second serving cell; and generatingthe HARQ ACK/NACK signal comprising the first HARQ ACK/NACKs and thesecond HARQ ACK/NACKs.
 7. The method of claim 6, wherein the first HARQACK/NACKs and the second HARQ ACK/NACKs are combined based on a PhysicalUplink Control Channel (PUCCH) resource index and a constellation of amodulation symbol, and wherein the first HARQ ACK/NACKs and the secondHARQ ACK/NACKs are transmitted through a PUCCH format 1/1 a/1b with achannel selection, a PUCCH format 3, or a Physical Uplink Shared Channel(PUSCH).
 8. A method of communicating control information between a basestation and a user equipment (UE), the method comprising: establishing aRadio Resource Control (RRC) connection with the UE through a firstserving cell, the first serving cell supporting a Time Division Duplex(TDD) mode; transmitting an RRC message to the UE through the firstserving cell, the RRC message comprising carrier aggregation (CA)configuration information, the CA configuration information comprisinginformation of a second serving cell supporting a Frequency DivisionDuplex (FDD) mode, and the first serving cell and the second servingcell being aggregated by a TDD-FDD CA scheme; configuring a 2-bitdownlink (DL) downlink assignment index (DAI) field in a DL downlinkcontrol information (DCI) format, the DL DCI format indicating aPhysical Downlink Shared Channel (PDSCH) transmission on the secondserving cell, and the 2-bit DL DAI field indicating that ten downlinksubframes for the second serving cell are associated with a uplinksubframe; transmitting, to the UE, at least one of a Physical DownlinkControl Channel (PDCCH) and an Enhanced PDCCH (EPDCCH), the at least oneof the PDCCH and the EPDCCH comprising the DL DCI format; transmitting,to the UE, data through the first serving cell and the second servingcell; and in response to the transmitted data, receiving a HybridAutomatic Repeat reQuest (HARQ) Acknowledgement/Negative Acknowledgement(ACK/NACK) signal, the HARQ ACK/NACK signal being indexed based on avalue of the 2-bit DL DAI field, wherein the HARQ ACK/NACK signal isreceived through the uplink subframe of the first serving cell.
 9. Themethod of claim 8, further comprising: configuring a 2-bit uplink (UL)DAI field in a UL DCI format, the UL DCI format indicating a PhysicalUplink Shared Channel (PUSCH) transmission on the second serving cell.10. The method of claim 8, wherein, if the value of the 2-bit DL DAIfield corresponds to 2, the value of the 2-bit DL DAI field indicatesthat at least one of the number of subframes with the PDSCH transmissionand the number of subframes with the PDCCH or the EPDCCH indicating DLSemi-Persistent Scheduling (SPS) release is 2, 6, or
 10. 11. The methodof claim 8, further comprising: configuring a most significant bit (MSB)of the 2-bit DL DAI field as zero (0) and a least significant bit (LSB)of the 2-bit DL DAI field as one (1).
 12. The method of claim 8, whereinthe 2-bit DL DAI field is defined in the following Table: Number ofsubframes having PDSCH and DAI number of subframes having MSB, V^(UL)_(DAI) or PDCCH/EPDCCH indicating DL Semi- LSB V^(DL) _(DAI) PersistentScheduling (SPS) release 0, 0 1 1 or 5 or 9 0, 1 2 2 or 6 or 10 1, 0 3 3or 7 1, 1 4 0 or 4 or 8 wherein the MSB is a most significant bit, theLSB is a least significant bit, V^(UL) _(DAI) denotes a value of a ULDAI field, and V^(DL) _(DAI) denotes the value of the DL DAI field.


13. The method of claim 8, wherein the HARQ ACK/NACK signal comprising:first HARQ ACK/NACKs indexed based on the value of the 2-bit DL DAIfield, the first HARQ ACK/NACKs being responsive to the data transmittedthrough subframes of the first serving cell; and second HARQ ACK/NACKsindexed based on the value of the 2-bit DL DAI field, the second HARQACK/NACKs being responsive to the data transmitted through subframes ofthe second serving cell.
 14. The method of claim 13, wherein the firstHARQ ACK/NACKs and the second HARQ ACK/NACKs are combined based on aPhysical Uplink Control Channel (PUCCH) resource index and aconstellation of a modulation symbol, and wherein the first HARQACK/NACKs and the second HARQ ACK/NACKs are transmitted through a PUCCHformat 1/1a/1b with a channel selection, a PUCCH format 3, or a PhysicalUplink Shared Channel (PUSCH).